dorm2r.c File Reference

(r)

Functions
int	dorm2r_fla (char *side, char *trans, integer *m, integer *n, integer *k, doublereal *a, integer *lda, doublereal *tau, doublereal *c__, integer *ldc, doublereal *work, integer *info)

Function Documentation

dorm2r_fla()

int dorm2r_fla	(	char *	side,
		char *	trans,
		integer *	m,
		integer *	n,
		integer *	k,
		doublereal *	a,
		integer *	lda,
		doublereal *	tau,
		doublereal *	c__,
		integer *	ldc,
		doublereal *	work,
		integer *	info
	)

{
    /* System generated locals */
    integer a_dim1, a_offset, c_dim1, c_offset, i__1, i__2;
    /* Local variables */
    integer i__, i1, i2, i3, ic, jc, mi, ni, nq;
    doublereal aii;
    logical left;
    extern /* Subroutine */
    int dlarf_(char *, integer *, integer *, doublereal *, integer *, doublereal *, doublereal *, integer *, doublereal *);
    extern logical lsame_(char *, char *);
    extern /* Subroutine */
    int xerbla_(char *, integer *);
    logical notran;
    /* -- LAPACK computational routine (version 3.4.2) -- */
    /* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
    /* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
    /* September 2012 */
    /* .. Scalar Arguments .. */
    /* .. */
    /* .. Array Arguments .. */
    /* .. */
    /* ===================================================================== */
    /* .. Parameters .. */
    /* .. */
    /* .. Local Scalars .. */
    /* .. */
    /* .. External Functions .. */
    /* .. */
    /* .. External Subroutines .. */
    /* .. */
    /* .. Intrinsic Functions .. */
    /* .. */
    /* .. Executable Statements .. */
    /* Test the input arguments */
    /* Parameter adjustments */
    a_dim1 = *lda;
    a_offset = 1 + a_dim1;
    a -= a_offset;
    --tau;
    c_dim1 = *ldc;
    c_offset = 1 + c_dim1;
    c__ -= c_offset;
    --work;
    /* Function Body */
    *info = 0;
    left = lsame_(side, "L");
    notran = lsame_(trans, "N");
    /* NQ is the order of Q */
    if (left)
    {
        nq = *m;
    }
    else
    {
        nq = *n;
    }
    if (! left && ! lsame_(side, "R"))
    {
        *info = -1;
    }
    else if (! notran && ! lsame_(trans, "T"))
    {
        *info = -2;
    }
    else if (*m < 0)
    {
        *info = -3;
    }
    else if (*n < 0)
    {
        *info = -4;
    }
    else if (*k < 0 || *k > nq)
    {
        *info = -5;
    }
    else if (*lda < max(1,nq))
    {
        *info = -7;
    }
    else if (*ldc < max(1,*m))
    {
        *info = -10;
    }
    if (*info != 0)
    {
        i__1 = -(*info);
        xerbla_("DORM2R", &i__1);
        return 0;
    }
    /* Quick return if possible */
    if (*m == 0 || *n == 0 || *k == 0)
    {
        return 0;
    }
    if (left && ! notran || ! left && notran)
    {
        i1 = 1;
        i2 = *k;
        i3 = 1;
    }
    else
    {
        i1 = *k;
        i2 = 1;
        i3 = -1;
    }
    if (left)
    {
        ni = *n;
        jc = 1;
    }
    else
    {
        mi = *m;
        ic = 1;
    }
    i__1 = i2;
    i__2 = i3;
    for (i__ = i1;
            i__2 < 0 ? i__ >= i__1 : i__ <= i__1;
            i__ += i__2)
    {
        if (left)
        {
            /* H(i) is applied to C(i:m,1:n) */
            mi = *m - i__ + 1;
            ic = i__;
        }
        else
        {
            /* H(i) is applied to C(1:m,i:n) */
            ni = *n - i__ + 1;
            jc = i__;
        }
        /* Apply H(i) */
        aii = a[i__ + i__ * a_dim1];
        a[i__ + i__ * a_dim1] = 1.;
        dlarf_(side, &mi, &ni, &a[i__ + i__ * a_dim1], &c__1, &tau[i__], &c__[ ic + jc * c_dim1], ldc, &work[1]);
        a[i__ + i__ * a_dim1] = aii;
        /* L10: */
    }
    return 0;
    /* End of DORM2R */
}

References i.

Referenced by dormqr_fla().